Modular, exchangeable surge protection system

ABSTRACT

A surge protection system provides surge protection to a load. The load is connected to a breaker panel through the surge protection system and a surge protection module bridges the hot/neutral/ground such that the surge protection module absorbs surges from the breaker panel and beyond. Being that, after exposure to certain amounts of surges, the surge protection modules lose effectiveness for surge protection, the surge protection module is removable and replaceable by a user without risk of personal injury from shock caused by making personal contact with electrical power. During removal and replacement, the load remains in electrical connection to the breaker panel.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/477,744 filed on Apr. 3, 2017 which, in turn, claims thebenefit of U.S. provisional application No. 62/466,688 filed on Mar. 3,2017, the disclosure of which is incorporated by reference.

FIELD

This invention relates to the field of electrical surge protection andmore particularly to a system for providing surge protection to one ormore circuits in a modular fashion.

BACKGROUND

There are many situations in which surge protection is desired toprotect equipment from electrical surges caused by nature or power-linefluctuations. Electronic surge protection components known in theindustry include, for example, metal-oxide varistors, arc gaps, gasdischarge tubes, etc.

As the known electronic surge protection components are exposed topower-line surges, the electronic surge protection components absorbmuch of the energy of the surge, limiting the amount of surge energygetting to other equipment on the power line(s). Each time theelectronic surge protection components absorb such energy, the life ofsuch electronic surge protection components decreases, until, eventuallythere is little surge protection capability remaining, at which time,the power-line circuit that was protected by that surge protectioncomponents is no longer protected.

Often, several surge protectors are deployed to protect individualcircuits of an electrical wiring system. Take for example, a gas stationarrangement having a car wash, lighting, several dispensing bays, carvacuum systems, an air compressor, inside-store register systems, insidelighting, refrigeration, etc. It is important to have each individualcircuit of such an arrangement individually protected so if the powergrid experiences a surge, the surge from the power grid is mitigatedbefore reaching the devices on each protected circuit and so that if oneof the devices (e.g., the outdoor lighting) on the protected circuitexperiences a surge, the surge is mitigated before reaching devices onother circuits.

In the past, surge protection systems offered multiple circuitprotection, but as discussed above, as surges occur in one or severalcircuits, the entire surge protection system need be replaced orrepaired, requiring removal by an experienced electrician. During thetime when such surge protection systems are being repaired/replaced,each circuit protected by such surge protection systems go without poweruntil the surge protection system is replaced, which is not desired asmany such applications require 24-hour operation and shutting downseveral circuits to replace a multi-circuit surge protection systemoften requires closing the entire operation (e.g., lack of lighting isnot acceptable for safety reasons, etc.).

What is needed is a system that will provide for individual replacementof surge protection for individual circuits without the need of anelectrician.

SUMMARY

A surge protection system provides surge protection to one or morecircuits. Each circuit is connected to power and a surge protectionmodule bridges the circuit such that the surge protection module absorbssurges from the power and/or the circuit. Being that, after exposure tocertain amounts of surges, the surge protection modules loseeffectiveness for surge protection, each surge protection module isindependently removable and replaceable by a user without risk ofpersonal injury from shock caused by making personal contact with thepower and/or circuit. In some embodiments, a filter circuit is providedto filter out noise on the circuit. It is anticipated that theprotection module includes one or more indicators to inform a user thatthe protection circuit is operational and whether protection has beenlost. Further, in some embodiments, a fuse is provided to protect thecircuit from over current.

In one embodiment, a surge protection system for inserting between powerfrom a breaker panel and a single load includes a main board having afirst connector for connecting to input power from the breaker panel, asecond connector for connecting to the single load, an electricalconnection between the first connector and the second connector, and aprotection module safety connector bridging the electrical connection,the protection module safety connector having recessed contacts. Therecessed contacts providing protection from electric shock. A surgeprotection module removably connected to the protection module safetyconnector. The surge protection module has at least one componentconnected to the electrical connection through the protection modulesafety connector. Power from the breaker panel and power to the singleload is not exposed for human touch. The first connector remainselectrically connected to the second connector when the surge protectionmodule is removed, thereby providing power from the breaker panel to thesingle load even after the surge protection module is removed.

In another embodiment, a surge protection system interfaced between abreaker panel and a single load includes a main board having a firstconnector for connecting to input power from the breaker panel, a secondconnector for connecting to the single load that is to be protected, anelectrical connection between the first connector and the secondconnector, and a protection module safety connector bridging theelectrical connection. The protection module safety connector havingrecessed contacts for protection from electric shock. A surge protectionmodule is connected to the protection module safety connector. The surgeprotection module has a first metal oxide varistor connected between aline potential of the electrical connection and a neutral potential ofthe electrical connection and a second metal oxide varistor connectedbetween a line potential of the electrical connection and earth groundpotential of the electrical connection. The input power or power to thecircuit is not exposed for human touch. The single load remainselectrically connected to the breaker panel when the surge protectionmodule is removed, thereby providing power from the breaker panel to thesingle load even after the surge protection module is removed.

In another embodiment, a method of protecting a single load includesconnecting the single load to a first connector of a surge protectionsystem and connecting a second connector of the surge protection systemto a breaker panel. The surge protection system electrically connects ahot conductor, a neutral conductor, and a ground conductor from thesingle load to the breaker panel. A surge protection module isconnected/plugged into a protection module safety connector of the surgeprotection system; thereby the surge protection module bridging the hotconductor, the neutral conductor, and the ground conductor. Removal ofthe surge protection module from the protection module safety connectordoes not interrupt power delivery from the breaker panel to the singleload.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be best understood by those having ordinary skill inthe art by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a plan view of a surge protection system of thepresent invention.

FIG. 2 illustrates a plan view of a connection block of the surgeprotection system.

FIG. 3 illustrates a plan view of a second connection block of the surgeprotection system.

FIG. 4 illustrates a cut-away elevation view of the surge protectionsystem.

FIG. 5 illustrates an elevation view of a protection module safetyconnector of the surge protection system.

FIG. 6 illustrates a perspective view of the surge protection systemwith a single surge protection module installed.

FIG. 7 illustrates a plan view of a panel of one of the surge protectionmodules.

FIG. 8 illustrates a schematic diagram of the main circuit board of thesurge protection system.

FIG. 9 illustrates a schematic diagram of the surge protection module ofthe surge protection system.

FIG. 10 illustrates a perspective view of the surge protection systemwith a single surge protection module.

FIG. 11 illustrates a schematic view of the surge protection system witha single surge protection module.

DETAILED DESCRIPTION

Reference will now be made in detail to the presently preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Throughout the following detailed description,the same reference numerals refer to the same elements in all figures.

Throughout this description, the term circuit is used to describe apower-distribution circuit to one or more devices. For example, in theUnited States, this is typically a 120 VAC or 240 VAC, 60 Hz circuit,but there is no limitation on the voltage, AC or DC, frequency, etc., asother countries and/or applications operate on different voltages andfrequencies.

Throughout this description, the term “electrician” is used to describea technician that is trained and/or licensed to work around liveelectrical circuits. For example, a gas-station owner is not typicallyan “electrician,” and, therefore, would not be qualified to take on thetask of replacing a surge protection device of prior, as there is oftendanger in disconnecting and reconnecting of the live wires of thecircuit, etc.

Throughout this description, for example purposes, a twelve-circuitprotection system is described, though it is fully anticipated that anynumber of circuits be protected from one circuit to many circuits, asneeded and practical.

Referring to FIG. 1, a plan view of a surge protection system 8 of thepresent invention is shown. The surge protection system 8 includes oneor more surge protection modules 40 that are replaceable, eachcontaining the active surge protection components for protecting acircuit from surges. The surge protection system 8 has a series ofconnection blocks 12/14 for connecting to power (e.g. power from themain line) and for connecting to each circuit. The connection blocks12/14 are wired such that the surge protection system 8 is easilyinstalled with exchangeability between power inputs on one side andcircuit connections on the other and vice versa. In this, as shown indetail in FIGS. 2 and 3, there is a neutral connection 12N/14N, a groundconnection 12G/14G, a first hot connection 12H1/14H1, and a second hotconnection 12H2.14H2 on each connection block 12/14. In this way, thepower line in is connected to the first hot connection 12H1/14H1 and thepower to the circuit is connected to the second hot connection12H2/14H2, providing an easy way to configure the surge protectionsystem 8 with inputs/outputs on either side, as desired.

As with most protection devices, a fuse 20 is provided in each circuitto limit current to the circuit being protected. It is fully anticipatedthat in some embodiments, no fuse 20 is present, though it is highlydesired to have fuses 20.

Also, optional filter circuits 22 are provided to filter out noise oneach circuit. Note that, although the filter circuits 22 are anticipatedto be located on the main board 10 or within the surge protectionmodules 40, it is anticipated that the filter circuits 22 be on the mainboard 10, since the filter circuits 22 do not degrade as surges occur.

As discussed above, it is a goal to provide replaceability of surgeprotection modules 40 that have failed without the need of excessivedown-time, and without the need of an electrician. To this, the surgeprotection system 8 is housed within, for example, an enclosure 6 (seeFIG. 4) and all high-voltage points (e.g. fuses 20 and connection blocks12/14 are covered/insulated from exposure by an insulating material 11so that whoever changes the surge protection modules 40 has littlechance of electrocution. Further, as will be shown in FIGS. 5 and 6, theprotection module safety connector 25 for connecting the surgeprotection modules 40 to the main board 10 has recessed conductors26N/26H/30G/32S to shield the user from dangerous voltages. Therefore,removal of the surge protection module 40 does not interrupt powerprovided to the protected circuit.

Referring to FIGS. 2 and 3, detailed plan views of connection blocks12/14 of the surge protection system 8 is shown. The connection blocks12/14 are wired such that the surge protection system 8 is easilyinstalled with exchangeability between power input connected to thefirst connection block 12 and output circuits connected to the secondconnection block 14 or, alternatively, power input connected to thesecond connection block 14 and output circuits connected to the firstconnection block 12. In this, there is a neutral connection 12N/14N, aground connection 12G/14G, a first hot connection 12H1/14H1, and asecond hot connection 12H2.14H2 on each connection block 12/14. In thisway, the power line in is connected to the first hot connection12H1/14H1 and the power to the circuit is connected to the second hotconnection 12H2/14H2, providing an easy way to configure the surgeprotection system 8 with inputs/outputs on either side, as desired.

Referring to FIG. 4, a cut-away elevation view of the surge protectionsystem 8 is shown. Although any suitable enclosure is anticipated, inthis example, the main board 10 is held within an enclosure 6 (typicallya metal enclosure) that has a cover 7 that is attached to the enclosure6, for example by a hinge 5. Note that the cover 7 is made of anymaterial, though a translucent or transparent material is anticipated toprovide a quick view of the indicators 42/44/46/48 of the surgeprotection modules 40 for quick identification of which surge protectionmodule 40 that has failed. In FIG. 4, the filter circuits 22 are shownmounted to the main board 10 and the fuses 20 sit in fuse clips 21 forquick replacement (e.g., by an electrician).

The surge protection modules 40 have internal connectors that receivethe respective protection module safety connectors 25, one of which isshown in detail in FIG. 5. Each protection module safety connector 25 isshown having a leg for a hot connection 26, a leg for a neutralconnection 28, a leg for a ground connection 30, and a leg for asignaling connection 32 (e.g. to signal status to a remote location).The number of conductors within the protection module safety connector25 in this example is four, though in other embodiments, two, three, ormore conductors is anticipated.

Referring to FIG. 5, an elevation view of a protection module safetyconnector 25 of the surge protection system 8 is shown. Each protectionmodule safety connector 25 is shown having a leg for a hot connection26, a leg for a neutral connection 28, a leg for a ground connection 30,and a leg for a signaling connection 32 (e.g. to signal status to aremote location). The number of conductors 26H/28N/30G/32S within theprotection module safety connector 25 in this example is four, though inother embodiments, two, three, or more conductors is anticipated. Notethat each of the conductors 26H/28N/30G/32S are recessed within therespective leg (leg for a hot connection 26, a leg for a neutralconnection 28, a leg for a ground connection 30, and a leg for asignaling connection 32) to protect from inadvertent contact by a userreplacing a surge protection module 40 with potentially dangerous powerlevels. This recessed contact operates in a similar fashion to standardpower outlets in one's home.

Referring to FIG. 6, a perspective view of the surge protection system 8with a single surge protection module 40 installed is shown. The mainboard 10 is shown out of the enclosure 6 and the single surge protectionmodule 40 is installed onto the protection module safety connector 25.Also visible are the connection blocks 12/14 and the fuses 20.

Referring to FIG. 7, a plan view of an indicator panel of one of thesurge protection modules 40 is shown. So that the user (e.g. shopkeeper, station owner, etc.) knows that each circuit is protected andthe status of each surge protection module 40, one or more indicators42/44/46/48 are provided on the face of each surge protection module 40.

After a surge protection system 8 is exposed to one or more surges, itis anticipated that one or more of the surge protection modules 40weaken or fail. Such weakening or failure is detected by circuitrywithin each surge protection module 40 and indicated on the one or moreindicators 42/44/46/48 and/or communicated electronically to a remotesystem through the signal connection 32S. By making the surge protectionmodules 40 replaceable by those other than an electrician, a user (forexample, a shop owner, gas station manager, etc.) seeing an indicator42/44/46/48 that indicates loss of surge protection is able to remove asurge protection module 40 that has failed and replace that surgeprotection module 40 with a new surge protection module 40. In this way,the user is able to order spare surge protection modules 40 or, upondetecting a failure, the user is able to order a new surge protectionmodule 40 from the manufacturer (e.g., for overnight shipping, etc.).

Referring to FIG. 8, a schematic diagram of the main board 10 of thesurge protection system 8 is shown. In the exemplary wiring schemeshown, each connection block 12/14 has two hot connections, hot-1 50 andhot-2 52. For example, the input power hot is connected to hot-2 52 oneither connection block 12/14 and the output power hot is connected tothe hot-1 50 on the other connection block 12/14, allowing forinterchangeable wiring from either side of the main board 10. Theneutral 54 and ground 56 are connected to respective neutral and groundconnections of each connection block 12/14. The fuse 20 protects thefilter circuit 22 and the surge protection module 40 (not shown in FIG.8), and the protected circuit from excessive current. I someembodiments, optic reflector sensors 74 are used to detect the presenceof each surge protection module 40 and interface to a dry-contactsignaling system 72 (as known in the industry) for reportingmissing/failed surge protection modules 40 to a remote site.

Referring to FIG. 9, a schematic diagram of the surge protection module40 of the surge protection system 8 is shown. The surge protectionmodule 40 has a connector 80 that mates with one of the protectionmodule safety connectors 25. The connector has a first contact 86H formating with the first recessed connector 26H of the main board forconnecting to the line (or “hot”) of the circuit that is being protectedfrom surges. The connector has a second contact 88N for mating with thesecond recessed connector 28N of the main board for connecting to theneutral of the circuit that is being protected from surges. Theconnector has a third contact 90G for mating with the third recessedconnector 30G of the main board for connecting to the ground of thecircuit that is being protected from surges. In some embodiments, theconnector has a fourth contact 92S for mating with the fourth recessedconnector 32S of the main board for relaying signaling information to aremote location.

Although many configurations, layouts, and implementations of a surgeprotection module 40 are anticipated, the exemplary schematic shown inFIG. 9 includes two metal-oxide varistors (MOVS) 47/49 with a firstmetal-oxide varistors (MOVS) 47 bridging the line and neutral and asecond metal-oxide varistors (MOVS) 49 bridging the line and ground(e.g. earth ground). Again, this is an example, and other embodimentsare fully anticipated, for example, a single metal-oxide varistors(MOVS) 47 bridging the line and neutral, etc.

In this embodiment, a transient voltage suppression diode 51 alsobridges the line and neutral, providing added protection from transientvoltage spikes.

As the metal-oxide varistors (MOVS) 47/49 absorb energy from circuitsurges, the metal-oxide varistors (MOVS) 47/49 weaken and, eventually,fail in an open mode—e.g. they no longer function to absorb substantialamounts of energy of a circuit surge. In some embodiments, themetal-oxide varistors (MOVS) 47/49 include signaling outputs that drivetwo indicators 42/48. The “Replace” indicator 48 illuminates when themetal-oxide varistors (MOVS) 47/49 indicate they can no longer absorbenergy from surges while the “Good” indicator 42 illuminates when themetal-oxide varistors (MOVS) 47/49 indicate they are in good condition.

In some embodiments, a “Grounded” indicator 44 illuminates when propergrounding to earth is present and, in some embodiments, an “Energize”indicator 44 illuminates when power is present in the protected circuit.

Referring to FIG. 10, a perspective view of the surge protection systemwith a single surge protection module 40 is shown. In this exemplaryembodiment, an enclosure 6A/7A is formed having a single safetyconnector 25 for accepting a single surge protection module 40. Theenclosure 6A/7A is a wall-mountable enclosure, preferably made fromacrylonitrile-butadiene-styrene (ABS). The surge protection system witha single surge protection module 40 is designed to protect, for example,fire alarm panels while providing audible and remote notification whenthe surge protection module 40 is removed or has expired. Priorprotection devices require a separate enclosure for UL approval.

The enclosure 6A/7A includes mounting holes for conduit adapters, asound port 97 for the audible alarm 95, and a single safety connector 25for accepting a single surge protection module 40 for self-servicingwith replacement surge protection modules 40.

The one or more indicators 42/44/46/48 of the surge protection module 40are easily viewed from across the room.

One or more conduit openings 89 are provided for electrical connections,one of which is filled with a plug 93 for safety reasons. The cover 7Aholds the surge protection module 40 and blocks exposure to high voltagewires within the box 6A, allowing for user exchange of the surgeprotection modules 40. In some embodiments, the cover 7A is affixed tothe box 6A by a plurality of screws 91.

In some embodiments, when the surge protection module 40 is removed fromthe safety connector 25, alarm information is transmitted to a remotelocation as described above. Further, in some embodiments, the audiblealarm 95 (e.g. piezo transducer, sounder) is operated when the surgeprotection module 40 fails or when the surge protection module 40 isremoved. In some such embodiments, the audible alarm 95 is delayed for aperiod of time such as one hour to enable a user to exchange surgeprotection modules 40 or recognize a failed surge protection module 40through the one or more indicators 42/44/46/48 before being interruptedby the sound generation.

Referring to FIG. 11, a schematic view of the surge protection systemwith a single surge protection module 40 is shown. The surge protectionsystem with a single surge protection module 40 is designed to protect,for example, fire alarm panels while providing audible and remotenotification when the surge protection module 40 is removed or hasexpired. In FIG. 11, it is clearly shown that the power from the source(e.g. breaker panel 110) is directly connected to the load 112 (e.g. afire alarm panel) so that, removal and replacement of the surgeprotection module 40 does not interrupt power to the load 112 which, initself, has the possibility of causing failure of the load 112 or, atthe least, disruption of functionality of the load 112. The hot (H),neutral (N), and ground (G) is connected directly from the source (e.g.breaker panel 110) to the load 112, with the surge protection module 40bridging the hot (H), neutral (N), and ground (G). In this way, removalof the surge protection module 40 does not disrupt power distribution.

Equivalent elements can be substituted for the ones set forth above suchthat they perform in substantially the same manner in substantially thesame way for achieving substantially the same result.

It is believed that the system and method as described and many of itsattendant advantages will be understood by the foregoing description. Itis also believed that it will be apparent that various changes may bemade in the form, construction and arrangement of the components thereofwithout departing from the scope and spirit of the invention or withoutsacrificing all of its material advantages. The form herein beforedescribed being merely exemplary and explanatory embodiment thereof. Itis the intention of the following claims to encompass and include suchchanges.

What is claimed is:
 1. A surge protection system for inserting betweenpower from a breaker panel and a single load, the surge protectionsystem comprising: a main board having a first connector for connectingto input power from the breaker panel, a second connector for connectingto the single load, an electrical connection between the first connectorand the second connector, and a protection module safety connectorbridging the electrical connection, the protection module safetyconnector having recessed contacts, the recessed contacts providingprotection from electric shock; and a surge protection module removablyconnected to the protection module safety connector, the surgeprotection module having at least one component connected to theelectrical connection through the protection module safety connector;whereas the power from the breaker panel and power to the single load isnot exposed for human touch; and whereas the first connector remainselectrically connected to the second connector when the surge protectionmodule is removed, thereby providing power from the breaker panel to thesingle load even after the surge protection module is removed.
 2. Thesurge protection system of claim 1, wherein the electrical connectioncomprises a hot connection, neutral connection, and ground connection.3. The surge protection system of claim 1, further comprising an audiblealarm interfaced to the surge protection module, the audible alarmemitting a noise upon removal of the surge protection module or uponfailure of the surge protection module.
 4. The surge protection systemof claim 1, further comprising a filter circuit interfaced to theelectrical connection.
 5. The surge protection system of claim 1,further comprising at least one indicator on the surge protectionmodule.
 6. The surge protection system of claim 5, wherein a firstindicator of the at least one indicator on the surge protection moduleindicates loss of surge protection.
 7. The surge protection system ofclaim 1, wherein the protection module safety connector provides a firstelectrical conductor to a neutral potential of the electricalconnection, a second electrical conductor to a line potential of theelectrical connection, and a third electrical conductor to an earthground potential of the electrical connection.
 8. The surge protectionsystem of claim 7, wherein the surge protection module comprises atleast one protection device bridging at least two of the firstelectrical conductor, the second electrical conductor, and the thirdelectrical conductor.
 9. The surge protection system of claim 8, whereinthe at least one protection device comprises a first metal oxidevaristor connected between the second electrical conductor and the firstelectrical conductor and a second metal oxide varistor connected betweenthe second electrical conductor and the third electrical conductor. 10.A surge protection system for inserting between power from a breakerpanel and a single load, the surge protection system comprising: a mainboard having a first connector for connecting to input power from thebreaker panel, a second connector for connecting to the single load thatis to be protected, an electrical connection between the first connectorand the second connector, and a protection module safety connectorbridging the electrical connection, the protection module safetyconnector having recessed contacts, the recessed contacts providingprotection from electric shock; and a surge protection module connectedto the protection module safety connector, the surge protection modulecomprising a first metal oxide varistor connected between a linepotential of the electrical connection and a neutral potential of theelectrical connection and a second metal oxide varistor connectedbetween a line potential of the electrical connection and earth groundpotential of the electrical connection; whereas the input power or powerto the circuit is not exposed for human touch; and whereas the singleload remains electrically connected to the breaker panel when the surgeprotection module is removed, thereby providing power from the breakerpanel to the single load even after the surge protection module isremoved.
 11. The surge protection system of claim 10, further comprisingan audible alarm interfaced to the surge protection module, the audiblealarm emitting a noise upon removal of the surge protection module orupon failure of the surge protection module.
 12. The surge protectionsystem of claim 10, further comprising a filter circuit interfaced tothe electrical connection.
 13. The surge protection system of claim 10,further comprising at least one indicator on the surge protectionmodule.
 14. The surge protection system of claim 13, wherein a firstindicator of the at least one indicator on the surge protection moduleindicates loss of surge protection.
 15. The surge protection system ofclaim 10, wherein the protection module safety connector provides afirst electrical conductor to the neutral potential of the electricalconnection, a second electrical conductor to the line potential of theelectrical connection, and a third electrical conductor to the earthground potential of the electrical connection.
 16. The surge protectionsystem of claim 15, wherein the protection module safety connectorprovides a fourth electrical conductor for signaling a status of thesurge protection module.
 17. A method of protecting a single load, themethod comprising: connecting the single load to a first connector of asurge protection system; connecting a second connector of the surgeprotection system to a breaker panel, the surge protection systemelectrically connecting a hot conductor, a neutral conductor, and aground conductor from the single load to the breaker panel; andconnecting a surge protection module to a protection module safetyconnector of the surge protection system, the surge protection modulethereby bridging the hot conductor, the neutral conductor, and theground conductor; whereas removing of the surge protection module fromthe protection module safety connector does not interrupt power deliveryfrom the breaker panel to the single load.
 18. The method of claim 17,further comprising: after an indication from the surge protection modulethat the surge protection module has failed, removing the surgeprotection module from the protection module safety connector andconnecting a new surge protection module to the protection module safetyconnector.
 19. The method of claim 18, wherein between the steps ofremoving the surge protection module and connecting the new surgeprotection module, the single load remains electrically connected to thebreaker panel.
 20. The method of claim 17, further comprising: emittingnoise from an audible alarm that is interfaced to the surge protectionmodule through the protection module safety connector after failing ofthe surge protection module.